fixup! [FLINK-17012][runtime] 'RUNNING' state split into 'RUNNING' an…

[akalash]

…d 'RECOVERING' in order to distinguish when the task is really running

What is the purpose of the change

fixup for #15221. Several places which allow RECOVERING state were added.

Brief change log

• It is possible to send the event in RECOVERING state

Verifying this change

This change is already covered by existing tests, from #15221.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (yes / no)
• The serializers: (yes / no / don't know)
• The runtime per-record code paths (performance sensitive): (yes / no / don't know)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn/Mesos, ZooKeeper: (yes / no / don't know)
• The S3 file system connector: (yes / no / don't know)

Documentation

• Does this pull request introduce a new feature? (yes / no)
• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)